A Deep, High‐Resolution Survey at 74 MHz

Abstract

We present a 74 MHz survey of a 165 deg 2 region located near the north Galactic pole. This survey has an unprecedented combination of both resolution (25″ FWHM) and sensitivity (σ as low as 24 mJy beam -1). We detect 949 sources at the 5 σ level in this region, enough to begin exploring the nature of the 74 MHz source population. We present differential source counts, spectral index measurements, and the size distribution as determined from counterparts in the high-resolution FIRST 1.4 GHz survey. We find a trend of steeper spectral indices for the brighter sources. Further, there is a clear correlation between spectral index and median source size, with the flat spectrum sources being much smaller on average. Ultra-steep spectrum objects (α ≤ -1.2; S ν ∝ ν α) are identified, and we present high-resolution VLA follow-up observations of these sources which, identified at such a low frequency, are excellent candidates for high-redshift radio galaxies.